A hydrogen atom in the ground state is excited by monochromatic radiation of wavelength \[\lambda \overset{o}{\mathop{A}}\,\]. The resulting spectrum consists of maximum 15 different lines. What is the wavelength \[\lambda \]?

\[1025\,\overset{o}{\mathop{A}}\,\]

\[937.3\,\overset{o}{\mathop{A}}\,\]

\[1025\,\overset{o}{\mathop{A}}\,\]

\[1236\,\overset{o}{\mathop{A}}\,\]

Which of the following sets of quantum numbers represent the highest stability of an atom?

\[n=4,\,\ell =1,\,m=0,\,s=+1/2\]

\[n=4,\,\ell =0,\,m=0,\,s=+1/2\]

\[n=4,\,\ell =2,\,m=1,\,s=+1/2\]

\[n=3,\,\ell =1,\,m=0,\,s=+1/2\]

Molar conductance's of \[BaC{{l}_{2}},{{H}_{2}}S{{O}_{4}}\] and HCl at infinite dilutions are \[{{x}_{1}},{{x}_{2}}\] and \[{{x}_{3}}\] respectively. Equivalent conductance of \[BaS{{O}_{4}}\] at infinite dilution will be:

\[({{x}_{1}}+{{x}_{2}}-{{x}_{3}})/2\]

\[{{x}_{1}}+{{x}_{2}}-2{{x}_{3}}\]

\[({{x}_{1}}-{{x}_{2}}-{{x}_{3}})/2\]

\[({{x}_{1}}+{{x}_{2}}-2{{x}_{3}})/2\]

Molar conductance of a 1.5 M solution of an electrolyte is found to be \[138.9\text{ }S\text{ }c{{m}^{2}}\]. The specific conductance of this solution is

\[0.102\text{ S}\,\text{c}{{\text{m}}^{-1}}\]

\[0.208\text{ S}\,\text{c}{{\text{m}}^{-1}}\]

\[0.102\text{ S}\,\text{c}{{\text{m}}^{-1}}\]

\[0.320\text{ S}\,\text{c}{{\text{m}}^{-1}}\]

\[0.152\text{ S}\,\text{c}{{\text{m}}^{-1}}\]

Given the following half reactions: \[{{A}^{2+}}+{{e}^{-}}\to {{A}^{+}},{{E}^{o}}=+1.70V\] \[{{B}^{2+}}+2{{e}^{-}}\to {{B}^{+}},{{E}^{o}}=+0.60V\] \[{{C}^{3+}}+{{e}^{-}}\to {{C}^{2+}},{{E}^{o}}=+0.90V\] The only reaction that could be used in titration would be

\[{{C}^{2+}}\] with \[{{B}^{4+}}\]

\[{{A}^{+}}\] with \[{{B}^{4+}}\]

\[{{A}^{+}}\] with \[{{C}^{3+}}\]

\[{{A}^{2+}}\] with \[{{C}^{2+}}\]

\[{{C}^{2+}}\] with \[{{B}^{4+}}\]

Given (i) \[Mn{{O}_{4}}^{-}+8{{H}^{+}}+5{{e}^{-}}\xrightarrow{{}}\]\[M{{n}^{2+}}+4{{H}_{2}}\,O\] (ii) \[Mn{{O}_{2}}+4{{H}^{+}}+2{{e}^{-}}\xrightarrow{{}}\]\[M{{n}^{2+}}+2{{H}_{2}}\,O{{E}^{0}}={{x}_{2}}V\] Find \[{{E}^{0}}\] for the following reaction \[Mn{{O}_{4}}^{-}+4{{H}^{+}}+3{{e}^{-}}\xrightarrow{{}}Mn{{O}_{2}}+2{{H}_{2}}\,O\]

\[\frac{2{{x}_{1}}-5{{x}_{2}}}{3}\]

\[\frac{5{{x}_{1}}-2{{x}_{2}}}{3}\]

\[\frac{2{{x}_{1}}-5{{x}_{2}}}{3}\]

The equivalent weight of\[Zn{{\left( OH \right)}_{2}}\]in the following reaction is equal to its, \[[Zn{{\left( OH \right)}_{2}}+\text{ }\left( N{{O}_{3}} \right)~Zn\left( OH \right)\left( N{{O}_{3}} \right)\text{ }+{{H}_{2}}O]\] [MH CET 1999]

\[3\times \text{formula}\ \text{wt}\text{.}\]

\[\frac{\text{Formula}\ \text{wt}\text{.}}{2}\]

\[\frac{\text{Formula}\ \text{wt}\text{.}}{1}\]

\[3\times \text{formula}\ \text{wt}\text{.}\]

\[2\times \text{formula}\ \text{wt}\text{.}\]

Which one of the following statements is correct in reversible reaction. A catalyst [MP PET 1994; EAMCET 1987]

Alters the equilibrium constant of the reaction

Increases the rate of forward reaction

Decreases the rate of forward reaction

Increases the rate of backward and forward reactions

Alters the equilibrium constant of the reaction

Ionic radii are [CBSE PMT 2003, 04]

Inversely proportional to square of effective nuclear charge.

Directly proportional to effective nuclear charge

Directly proportional to square of effective nuclear charge

Inversely proportional to effective nuclear charge

Inversely proportional to square of effective nuclear charge.

Acquired immune deficiency syndroms (AIDS) is characterised [AIIMS 2000]

Reduction in number of helper T-cells

Inability of body to produce interferons

One mole of calcium phosphide on reaction with excess of water gives [IIT 1999]

One mole of phosphorus pentoxide

The vapor density of completely dissociated \[N{{H}_{4}}Cl\] would be [NCERT 1974]

Double that of \[N{{H}_{4}}Cl\]

Slight less than half that of \[N{{H}_{4}}Cl\]

Double that of \[N{{H}_{4}}Cl\]

Determined by the amount of solid \[N{{H}_{4}}Cl\] in the experiment

Lead is not affected by dil. \[HCl\] in cold because

\[Pb{{O}_{2}}\] film is always present on Pb surface, which resist chemical attack

Pb is less electronegative than H

PbO film is formed which resists chemical attack by acid

\[PbC{{l}_{2}}\] protective coating gets formed on Pb surface

\[Pb{{O}_{2}}\] film is always present on Pb surface, which resist chemical attack

Consider an endothermic reaction \[X\to Y\] with the activation energies \[{{E}_{b}}\] and \[{{E}_{f}}\] for the backward and forward reactions, respectively, in general [AIEEE 2005]

There is no definite relation between \[{{E}_{b}}\] and \[{{E}_{f}}\]

Of the following sets which one does NOT contain isoelectronic species [AIEEE 2005]

\[BO_{3}^{3-},\,CO_{3}^{2-},\,NO_{3}^{-}\]

\[PO_{4}^{3-},\,SO_{4}^{2-},\,ClO_{4}^{-}\]

\[C{{N}^{-}},\,{{N}_{2}},\,C_{2}^{2-}\]

\[SO_{3}^{2-},\,CO_{3}^{2-},\,NO_{3}^{-}\]

\[BO_{3}^{3-},\,CO_{3}^{2-},\,NO_{3}^{-}\]

The role of fluorspar \[(Ca{{F}_{2}})\] which is added in small quantities in the electrolytic reduction of alumina dissolved in fused cryolite \[(N{{a}_{3}}Al{{F}_{6}})\] is

to increase the temperature of the melt.

to make the fused mixture very conducting

to increase the temperature of the melt.

to decrease the rate of oxidation of carbon at the anode.

11242 + Mcqs in Chemistry in Joint Entrance Exam - Main (JEE Main) Page 9 McqOptions

401.	A hydrogen atom in the ground state is excited by monochromatic radiation of wavelength \[\lambda \overset{o}{\mathop{A}}\,\]. The resulting spectrum consists of maximum 15 different lines. What is the wavelength \[\lambda \]?
A.	\[937.3\,\overset{o}{\mathop{A}}\,\]
B.	\[1025\,\overset{o}{\mathop{A}}\,\]
C.	\[1236\,\overset{o}{\mathop{A}}\,\]
D.	None of these
Answer» B. \[1025\,\overset{o}{\mathop{A}}\,\]

Discussion

402.	Which of the following sets of quantum numbers represent the highest stability of an atom?
A.	\[n=4,\,\ell =1,\,m=0,\,s=+1/2\]
B.	\[n=4,\,\ell =0,\,m=0,\,s=+1/2\]
C.	\[n=4,\,\ell =2,\,m=1,\,s=+1/2\]
D.	\[n=3,\,\ell =1,\,m=0,\,s=+1/2\]
Answer» E.

Discussion

403.	From the following list of atoms, choose the no. of pairs of isotopes, isobars and isotones respectively \[_{8}^{16}O,\,_{19}^{39}K,\,_{19}^{335}U,\,_{19}^{40}K,\,_{7}^{14}N,\,_{8}^{18}O,\,_{6}^{14}C,\,_{20}^{40}Ca,\,_{92}^{238}U\]
A.	3, 2, 2
B.	2, 3, 2
C.	2, 2, 3
D.	2, 2, 2
Answer» B. 2, 3, 2

Discussion

404.	Arrange the following particles in increasing order of values of e/m ratio : electron (e), proton (p), neutron (n) and \[\alpha -\]particle \[(\alpha )\]
A.	\[n,\,p,\,e,\,\alpha \]
B.	\[n,\,\alpha ,\,p,\,e\]
C.	\[n,\,p,\,\alpha ,\,e\]
D.	\[e,\,p,\,n,\,\alpha \]
Answer» C. \[n,\,p,\,\alpha ,\,e\]

Discussion

405.	The maximum valency of an element with atomic number 7 is [AFMC 2002]
A.	2
B.	5
C.	4
D.	3
Answer» C. 4

Discussion

406.	Which of the following group of elements eliminates electron easily
A.	N, P, As
B.	O, S, Se
C.	Li, Na, K
D.	Cl, Ba, I
Answer» D. Cl, Ba, I

Discussion

407.	The mass of \[{{N}_{2}}{{F}_{4}}\] produced by the reaction of 2.0 g of \[N{{H}_{3}}\] and 8.0 g of \[{{F}_{2}}\] is 3.56 g. What is the per cent yield?\[2N{{H}_{3}}+5{{F}_{2}}\to {{N}_{2}}{{F}_{4}}+6HF\]
A.	79.0
B.	71.2
C.	84.6
D.	None of these
Answer» E.

Discussion

408.	Example of a three-dimensional silicate is:
A.	Zeolites
B.	Ultramarines
C.	Feldspars
D.	Beryls
Answer» D. Beryls

Discussion

409.	Molar conductance's of \[BaC{{l}_{2}},{{H}_{2}}S{{O}_{4}}\] and HCl at infinite dilutions are \[{{x}_{1}},{{x}_{2}}\] and \[{{x}_{3}}\] respectively. Equivalent conductance of \[BaS{{O}_{4}}\] at infinite dilution will be:
A.	\[({{x}_{1}}+{{x}_{2}}-{{x}_{3}})/2\]
B.	\[{{x}_{1}}+{{x}_{2}}-2{{x}_{3}}\]
C.	\[({{x}_{1}}-{{x}_{2}}-{{x}_{3}})/2\]
D.	\[({{x}_{1}}+{{x}_{2}}-2{{x}_{3}})/2\]
Answer» E.

Discussion

410.	Molar conductance of a 1.5 M solution of an electrolyte is found to be \[138.9\text{ }S\text{ }c{{m}^{2}}\]. The specific conductance of this solution is
A.	\[0.208\text{ S}\,\text{c}{{\text{m}}^{-1}}\]
B.	\[0.102\text{ S}\,\text{c}{{\text{m}}^{-1}}\]
C.	\[0.320\text{ S}\,\text{c}{{\text{m}}^{-1}}\]
D.	\[0.152\text{ S}\,\text{c}{{\text{m}}^{-1}}\]
Answer» B. \[0.102\text{ S}\,\text{c}{{\text{m}}^{-1}}\]

Discussion

411.	Emf of the cell \[Ni\|N{{i}^{2+}}(0.1\,M)\|\|A{{u}^{3+}}\,(1.0\,M)\|\,Au\] will be \[(E_{Ni/N{{i}^{2+}}}^{{}^\circ }=0.25,\,E_{Au/A{{u}^{3+}}}^{{}^\circ }=1.5\,V)\]
A.	1.75 V
B.	\[+\]1.7795 V
C.	\[+\]0.7795 V
D.	\[-\]1.7795 V
Answer» C. \[+\]0.7795 V

Discussion

412.	Given the following half reactions: \[{{A}^{2+}}+{{e}^{-}}\to {{A}^{+}},{{E}^{o}}=+1.70V\] \[{{B}^{2+}}+2{{e}^{-}}\to {{B}^{+}},{{E}^{o}}=+0.60V\] \[{{C}^{3+}}+{{e}^{-}}\to {{C}^{2+}},{{E}^{o}}=+0.90V\] The only reaction that could be used in titration would be
A.	\[{{A}^{+}}\] with \[{{B}^{4+}}\]
B.	\[{{A}^{+}}\] with \[{{C}^{3+}}\]
C.	\[{{A}^{2+}}\] with \[{{C}^{2+}}\]
D.	\[{{C}^{2+}}\] with \[{{B}^{4+}}\]
Answer» D. \[{{C}^{2+}}\] with \[{{B}^{4+}}\]

Discussion

413.	Given the following molar conductivities at \[{{250}^{o}}C;HCl,425\,{{\Omega }^{-1}}c{{m}^{2}}mo{{l}^{-1}};\]\[NaCl\,\,125{{\Omega }^{-1}}\]\[c{{m}^{2}}mo{{l}^{-1}}\]NaC (sodium crotonate), \[82\,{{\Omega }^{-1}}c{{m}^{2}}mo{{l}^{-1}};\] what is the ionisation constant of crotonic acid? If the conductivity of a 0.001 M crotonic acid solution is \[3.82\times {{10}^{-4}}{{\Omega }^{-1}}c{{m}^{-1}}\]?
A.	\[1.5\times {{10}^{-4}}\]
B.	\[1.11\times {{10}^{-5}}\]
C.	\[2.11\times {{10}^{-5}}\]
D.	\[1.8\times {{10}^{-5}}\]
Answer» C. \[2.11\times {{10}^{-5}}\]

Discussion

414.	A cell diagram shown below contains one litre of Buffer solution \[HA(p{{K}_{a}}=8)\] and NaA in both compartment. What is the cell emf?
A.	0.81 V
B.	0.071 V
C.	0.0591 V
D.	1.182 V
Answer» D. 1.182 V

Discussion

415.	Given (i) \[Mn{{O}_{4}}^{-}+8{{H}^{+}}+5{{e}^{-}}\xrightarrow{{}}\]\[M{{n}^{2+}}+4{{H}_{2}}\,O\] (ii) \[Mn{{O}_{2}}+4{{H}^{+}}+2{{e}^{-}}\xrightarrow{{}}\]\[M{{n}^{2+}}+2{{H}_{2}}\,O{{E}^{0}}={{x}_{2}}V\] Find \[{{E}^{0}}\] for the following reaction \[Mn{{O}_{4}}^{-}+4{{H}^{+}}+3{{e}^{-}}\xrightarrow{{}}Mn{{O}_{2}}+2{{H}_{2}}\,O\]
A.	\[{{x}_{2}}-{{x}_{1}}\]
B.	\[{{x}_{1}}-{{x}_{2}}\]
C.	\[\frac{5{{x}_{1}}-2{{x}_{2}}}{3}\]
D.	\[\frac{2{{x}_{1}}-5{{x}_{2}}}{3}\]
Answer» D. \[\frac{2{{x}_{1}}-5{{x}_{2}}}{3}\]

Discussion

416.	The equivalent weight of\[Zn{{\left( OH \right)}_{2}}\]in the following reaction is equal to its, \[[Zn{{\left( OH \right)}_{2}}+\text{ }\left( N{{O}_{3}} \right)~Zn\left( OH \right)\left( N{{O}_{3}} \right)\text{ }+{{H}_{2}}O]\] [MH CET 1999]
A.	\[\frac{\text{Formula}\ \text{wt}\text{.}}{2}\]
B.	\[\frac{\text{Formula}\ \text{wt}\text{.}}{1}\]
C.	\[3\times \text{formula}\ \text{wt}\text{.}\]
D.	\[2\times \text{formula}\ \text{wt}\text{.}\]
Answer» C. \[3\times \text{formula}\ \text{wt}\text{.}\]

Discussion

417.	Which of the following is correct regarding ionization potential?
A.	\[O_{2}^{2+}>NO\]
B.	\[O_{2}^{2+}<NO\]
C.	\[O_{2}^{{}}<NO\]
D.	\[O_{2}^{2+}=NO\]
Answer» B. \[O_{2}^{2+}<NO\]

Discussion

418.	Which one of the following statements is correct in reversible reaction. A catalyst [MP PET 1994; EAMCET 1987]
A.	Increases the rate of forward reaction
B.	Decreases the rate of forward reaction
C.	Increases the rate of backward and forward reactions
D.	Alters the equilibrium constant of the reaction
Answer» D. Alters the equilibrium constant of the reaction

Discussion

419.	Ionic radii are [CBSE PMT 2003, 04]
A.	Directly proportional to effective nuclear charge
B.	Directly proportional to square of effective nuclear charge
C.	Inversely proportional to effective nuclear charge
D.	Inversely proportional to square of effective nuclear charge.
Answer» D. Inversely proportional to square of effective nuclear charge.

Discussion

420.	Which of the following is not a Lewis acid [J & K 2005]
A.	\[B{{F}_{3}}\]
B.	\[AlC{{l}_{3}}\]
C.	\[HCl\]
D.	\[LiAl{{H}_{4}}\]
Answer» E.

Discussion

421.	Acquired immune deficiency syndroms (AIDS) is characterised [AIIMS 2000]
A.	Killer T-cells
B.	Reduction in number of helper T-cells
C.	An autoimmune disease
D.	Inability of body to produce interferons
Answer» C. An autoimmune disease

Discussion

422.	Photon having wavelength 310 nm is used to break the bond of \[{{A}_{2}}\] molecule having bond energy \[288\,kg\,mo{{l}^{-1}}\] then % of energy of photon converted to the K.E. is \[[hc=12400\,ev\,\overset{o}{\mathop{A}}\,,\,1\,ev=96\,kJ/mol]\]
A.	25
B.	50
C.	75
D.	80
Answer» B. 50

Discussion

423.	Aqueous solution of a group 2 element is precipitated by adding \[N{{a}_{2}}C{{O}_{3}},\] then this precipitate is tested on flame, no light in visible region is observed , this element can be
A.	\[Ba\]
B.	\[Mg\]
C.	\[Ca\]
D.	\[Sr\]
Answer» C. \[Ca\]

Discussion

424.	Which compound has bond angle nearly to \[90{}^\circ \] [Pb. PMT 2001]
A.	\[{{H}_{2}}O\]
B.	\[{{H}_{2}}S\]
C.	\[N{{H}_{3}}\]
D.	\[C{{H}_{4}}\]
Answer» C. \[N{{H}_{3}}\]

Discussion

425.	In the analysis of basic radicals, the group reagent H2S gas is generally used in the groups [MP PMT 2003]
A.	I and II groups
B.	II and III groups
C.	III and V groups
D.	II and IV groups
Answer» E.

Discussion

426.	Which of the following is a disaccharide [CPMT 1990, 94]
A.	Lactose
B.	Starch
C.	Cellulose
D.	Glucose
Answer» B. Starch

Discussion

427.	An important insecticide is obtained by the action of chloral on chlorobenzene. It is [KCET 1989]
A.	BHC
B.	Gammexene
C.	DDT
D.	Lindane
Answer» D. Lindane

Discussion

428.	The harmone that helps in the conversion of glucose to glycogen in [CBSE PMT 2004]
A.	Adrenaline
B.	Insulin
C.	Cortisone
D.	Bile acids
Answer» C. Cortisone

Discussion

429.	One mole of calcium phosphide on reaction with excess of water gives [IIT 1999]
A.	One mole of phosphine
B.	Two moles of phosphoric acid
C.	Two moles of phosphine
D.	One mole of phosphorus pentoxide
Answer» D. One mole of phosphorus pentoxide

Discussion

430.	Which pair show cis-trans isomerism [RPET 1999]
A.	Maleic-fumaric acid
B.	Lactic-tartaric acid
C.	Malonic-succinic acid
D.	Crotonic-acrylic acid
Answer» B. Lactic-tartaric acid

Discussion

431.	Minimum resistance in bond rotation will be observed in the compound [RPMT 1999]
A.	Hexachloroethane
B.	Ethylene
C.	Acetylene
D.	Ethane
Answer» E.

Discussion

432.	In the standardization of \[N{{a}_{2}}{{S}_{2}}{{O}_{3}}\]using\[{{K}_{2}}C{{r}_{2}}{{O}_{7}}\]by iodometry, the equivalent weight of\[{{K}_{2}}C{{r}_{2}}{{O}_{7}}\] is [IIT-JEE (Screening) 2001]
A.	(Molecular weight)/2
B.	(Molecular weight)/6
C.	(Molecular weight)/3
D.	Same as molecular weight
Answer» C. (Molecular weight)/3

Discussion

433.	The approximate mass of tritium oxide molecule is
A.	18 amu
B.	20 amu
C.	22 amu
D.	24 amu
Answer» D. 24 amu

Discussion

434.	Molecular weight of heavy water is
A.	19
B.	18
C.	17
D.	20
Answer» E.

Discussion

435.	The vapor density of completely dissociated \[N{{H}_{4}}Cl\] would be [NCERT 1974]
A.	Slight less than half that of \[N{{H}_{4}}Cl\]
B.	Half that of \[N{{H}_{4}}Cl\]
C.	Double that of \[N{{H}_{4}}Cl\]
D.	Determined by the amount of solid \[N{{H}_{4}}Cl\] in the experiment
Answer» C. Double that of \[N{{H}_{4}}Cl\]

Discussion

436.	Lead is not affected by dil. \[HCl\] in cold because
A.	Pb is less electronegative than H
B.	PbO film is formed which resists chemical attack by acid
C.	\[PbC{{l}_{2}}\] protective coating gets formed on Pb surface
D.	\[Pb{{O}_{2}}\] film is always present on Pb surface, which resist chemical attack
Answer» D. \[Pb{{O}_{2}}\] film is always present on Pb surface, which resist chemical attack

Discussion

437.	Consider an endothermic reaction \[X\to Y\] with the activation energies \[{{E}_{b}}\] and \[{{E}_{f}}\] for the backward and forward reactions, respectively, in general [AIEEE 2005]
A.	\[{{E}_{b}}<{{E}_{f}}\]
B.	\[{{E}_{b}}>{{E}_{f}}\]
C.	\[{{E}_{b}}={{E}_{f}}\]
D.	There is no definite relation between \[{{E}_{b}}\] and \[{{E}_{f}}\]
Answer» B. \[{{E}_{b}}>{{E}_{f}}\]

Discussion

438.	A certain nuclide has a half-life period of 30 minutes. If a sample containing 600 atoms is allowed to decay for 90 minutes, how many atoms will remain [NCERT 1978]
A.	200 atoms
B.	450 atoms
C.	75 atoms
D.	500 atoms
Answer» D. 500 atoms

Discussion

439.	DIRECTION: Read the passage given below and answer the questions that follows: In hexagonal systems of crystals, a frequently encountered arrangement of atoms is described as a hexagonal prism. Here, the top and bottom of the cell are regular hexagons and three atoms sandwiched in between them. A space-of this model of this structure, called hexagonal close-packed (HCP), is constituted of a sphere on a flat surface surrounded in the same plane by six identical spheres as closely as possible. There spheres are then placed over the first layer so that they touch each other and represent the second layer. Each one of these three spheres touches three spheres of the bottom layer. Finally, the second layer is covered with third layer that is identical to the bottom layer in relative position. Assume radius of every sphere to be 'r'. The empty space in this HCP unit cell is
A.	0.74
B.	0.476
C.	0.32
D.	0.26
Answer» E.

Discussion

440.	Vitamin \[{{B}_{1}}\] is [MP PMT 2000]
A.	Riboflavin
B.	Cobalamin
C.	Thiamine
D.	Pyridoxine
Answer» D. Pyridoxine

Discussion

441.	Of the following sets which one does NOT contain isoelectronic species [AIEEE 2005]
A.	\[PO_{4}^{3-},\,SO_{4}^{2-},\,ClO_{4}^{-}\]
B.	\[C{{N}^{-}},\,{{N}_{2}},\,C_{2}^{2-}\]
C.	\[SO_{3}^{2-},\,CO_{3}^{2-},\,NO_{3}^{-}\]
D.	\[BO_{3}^{3-},\,CO_{3}^{2-},\,NO_{3}^{-}\]
Answer» D. \[BO_{3}^{3-},\,CO_{3}^{2-},\,NO_{3}^{-}\]

Discussion

442.	If two light nuclei are fused together in nuclear reaction the average energy per nucleon [Pb. PMT 2001]
A.	Increases
B.	Cannot be determined
C.	Remains same
D.	Decreases
Answer» E.

Discussion

443.	Which one of the following is a good conductor of electricity [MP PMT 1994; AFMC 2002]
A.	Diamond
B.	Graphite
C.	Silicon
D.	Amorphous carbon
Answer» C. Silicon

Discussion

444.	The \[\Delta H_{F}^{O}\] for \[C{{O}_{2}}(g),\,\,CO(g)\] and \[{{H}_{2}}O(g)\] are \[-\,393.5,\,-110.5\] and \[-\,241.8\text{ }kJ\text{ }mol\], respectively. The standard enthalpy change (in kJ) for the reaction \[C{{O}_{2(g)}}+{{H}_{2}}_{(g)}\xrightarrow{{}}C{{O}_{(g)}}+{{H}_{2}}{{O}_{(g)}}\] is:
A.	524.1
B.	+ 41.2
C.	- 262.5
D.	-41.2
Answer» C. - 262.5

Discussion

445.	If heat of dissociation of \[CHC{{l}_{2}}COOH\] is 0.7 kcal/mol, then \[\Delta H\] for the reaction: \[CHC{{l}_{2}}COOH+KOH\to CHC{{l}_{2}}COOK+{{H}_{2}}O\]
A.	- 13 kcal
B.	+ 13 kcal
C.	- 14.4 kcal
D.	- 13.7 kcal
Answer» B. + 13 kcal

Discussion

446.	One gram of an organic liquid X (molecular mass 78) liberates 160 J of heat on solidification. \[\Delta {{H}_{fusion}}\,\,(A)\] is:
A.	19.2 kJ/mol
B.	12.48 kJ/mol
C.	124.8 kJ/mol
D.	None of these
Answer» C. 124.8 kJ/mol

Discussion

447.	Natural rubber is which type of polymer [DCE 2002]
A.	Condensation polymer
B.	Addition polymer
C.	Co-ordination polymer
D.	None of these
Answer» C. Co-ordination polymer

Discussion

448.	The role of fluorspar \[(Ca{{F}_{2}})\] which is added in small quantities in the electrolytic reduction of alumina dissolved in fused cryolite \[(N{{a}_{3}}Al{{F}_{6}})\] is
A.	as a catalyst
B.	to make the fused mixture very conducting
C.	to increase the temperature of the melt.
D.	to decrease the rate of oxidation of carbon at the anode.
Answer» C. to increase the temperature of the melt.

Discussion

449.	A coffee cup calorimeter initially contains 125 g of water, at a temperature of \[24.2{}^\circ C\]. 8 g of ammonium nitrate \[(N{{H}_{4}}N{{O}_{3}}),\] also at \[24.2{}^\circ C,\] is added to the water, and the final temperature is \[18.2{}^\circ C\] what is the heat of solution of ammonium nitrate in kJ/mol? The specific heat capacity of the solution is \[4.2\text{ }J/{}^\circ Cg\].
A.	33.51 kJ/mol
B.	39.5 kJ/mol
C.	32.2 kJ/mol
D.	37.3 kJ/mol
Answer» B. 39.5 kJ/mol

Discussion

450.	Calculate the heat change in the reaction \[4\,N{{H}_{3}}(g)+3{{O}_{2}}(g)\to 2{{N}_{2}}(g)+6{{H}_{2}}O(\ell )\] at 298 K, given that the heats of formation at 298 K for \[N{{H}_{3}}(g)\] and \[{{H}_{2}}O(\ell )\] are - 46.0 and - 28.60 kJ \[mo{{l}^{-1}}\] respectively.
A.	- 1861 kJ
B.	- 1361 kJ
C.	- 1261 kJ
D.	- 1532 kJ
Answer» E.

Discussion

Explore topic-wise MCQs in Joint Entrance Exam - Main (JEE Main).

A hydrogen atom in the ground state is excited by monochromatic radiation of wavelength \[\lambda \overset{o}{\mathop{A}}\,\]. The resulting spectrum consists of maximum 15 different lines. What is the wavelength \[\lambda \]?

Which of the following sets of quantum numbers represent the highest stability of an atom?

From the following list of atoms, choose the no. of pairs of isotopes, isobars and isotones respectively \[_{8}^{16}O,\,_{19}^{39}K,\,_{19}^{335}U,\,_{19}^{40}K,\,_{7}^{14}N,\,_{8}^{18}O,\,_{6}^{14}C,\,_{20}^{40}Ca,\,_{92}^{238}U\]

Arrange the following particles in increasing order of values of e/m ratio : electron (e), proton (p), neutron (n) and \[\alpha -\]particle \[(\alpha )\]

The maximum valency of an element with atomic number 7 is [AFMC 2002]

Which of the following group of elements eliminates electron easily

The mass of \[{{N}_{2}}{{F}_{4}}\] produced by the reaction of 2.0 g of \[N{{H}_{3}}\] and 8.0 g of \[{{F}_{2}}\] is 3.56 g. What is the per cent yield?\[2N{{H}_{3}}+5{{F}_{2}}\to {{N}_{2}}{{F}_{4}}+6HF\]

Example of a three-dimensional silicate is:

Molar conductance's of \[BaC{{l}_{2}},{{H}_{2}}S{{O}_{4}}\] and HCl at infinite dilutions are \[{{x}_{1}},{{x}_{2}}\] and \[{{x}_{3}}\] respectively. Equivalent conductance of \[BaS{{O}_{4}}\] at infinite dilution will be:

Molar conductance of a 1.5 M solution of an electrolyte is found to be \[138.9\text{ }S\text{ }c{{m}^{2}}\]. The specific conductance of this solution is

Emf of the cell \[Ni|N{{i}^{2+}}(0.1\,M)||A{{u}^{3+}}\,(1.0\,M)|\,Au\] will be \[(E_{Ni/N{{i}^{2+}}}^{{}^\circ }=0.25,\,E_{Au/A{{u}^{3+}}}^{{}^\circ }=1.5\,V)\]

Given the following half reactions: \[{{A}^{2+}}+{{e}^{-}}\to {{A}^{+}},{{E}^{o}}=+1.70V\] \[{{B}^{2+}}+2{{e}^{-}}\to {{B}^{+}},{{E}^{o}}=+0.60V\] \[{{C}^{3+}}+{{e}^{-}}\to {{C}^{2+}},{{E}^{o}}=+0.90V\] The only reaction that could be used in titration would be

A cell diagram shown below contains one litre of Buffer solution \[HA(p{{K}_{a}}=8)\] and NaA in both compartment. What is the cell emf?

The equivalent weight of\[Zn{{\left( OH \right)}_{2}}\]in the following reaction is equal to its, \[[Zn{{\left( OH \right)}_{2}}+\text{ }\left( N{{O}_{3}} \right)~Zn\left( OH \right)\left( N{{O}_{3}} \right)\text{ }+{{H}_{2}}O]\] [MH CET 1999]

Which of the following is correct regarding ionization potential?

Which one of the following statements is correct in reversible reaction. A catalyst [MP PET 1994; EAMCET 1987]

Ionic radii are [CBSE PMT 2003, 04]

Which of the following is not a Lewis acid [J & K 2005]

Acquired immune deficiency syndroms (AIDS) is characterised [AIIMS 2000]

Photon having wavelength 310 nm is used to break the bond of \[{{A}_{2}}\] molecule having bond energy \[288\,kg\,mo{{l}^{-1}}\] then % of energy of photon converted to the K.E. is \[[hc=12400\,ev\,\overset{o}{\mathop{A}}\,,\,1\,ev=96\,kJ/mol]\]

Aqueous solution of a group 2 element is precipitated by adding \[N{{a}_{2}}C{{O}_{3}},\] then this precipitate is tested on flame, no light in visible region is observed , this element can be

Which compound has bond angle nearly to \[90{}^\circ \] [Pb. PMT 2001]

In the analysis of basic radicals, the group reagent H2S gas is generally used in the groups [MP PMT 2003]

Which of the following is a disaccharide [CPMT 1990, 94]

An important insecticide is obtained by the action of chloral on chlorobenzene. It is [KCET 1989]

The harmone that helps in the conversion of glucose to glycogen in [CBSE PMT 2004]

One mole of calcium phosphide on reaction with excess of water gives [IIT 1999]

Which pair show cis-trans isomerism [RPET 1999]

Minimum resistance in bond rotation will be observed in the compound [RPMT 1999]

In the standardization of \[N{{a}_{2}}{{S}_{2}}{{O}_{3}}\]using\[{{K}_{2}}C{{r}_{2}}{{O}_{7}}\]by iodometry, the equivalent weight of\[{{K}_{2}}C{{r}_{2}}{{O}_{7}}\] is [IIT-JEE (Screening) 2001]

The approximate mass of tritium oxide molecule is

Molecular weight of heavy water is

The vapor density of completely dissociated \[N{{H}_{4}}Cl\] would be [NCERT 1974]

Lead is not affected by dil. \[HCl\] in cold because

Consider an endothermic reaction \[X\to Y\] with the activation energies \[{{E}_{b}}\] and \[{{E}_{f}}\] for the backward and forward reactions, respectively, in general [AIEEE 2005]

A certain nuclide has a half-life period of 30 minutes. If a sample containing 600 atoms is allowed to decay for 90 minutes, how many atoms will remain [NCERT 1978]

Vitamin \[{{B}_{1}}\] is [MP PMT 2000]

Of the following sets which one does NOT contain isoelectronic species [AIEEE 2005]

If two light nuclei are fused together in nuclear reaction the average energy per nucleon [Pb. PMT 2001]

Which one of the following is a good conductor of electricity [MP PMT 1994; AFMC 2002]

The \[\Delta H_{F}^{O}\] for \[C{{O}_{2}}(g),\,\,CO(g)\] and \[{{H}_{2}}O(g)\] are \[-\,393.5,\,-110.5\] and \[-\,241.8\text{ }kJ\text{ }mol\], respectively. The standard enthalpy change (in kJ) for the reaction \[C{{O}_{2(g)}}+{{H}_{2}}_{(g)}\xrightarrow{{}}C{{O}_{(g)}}+{{H}_{2}}{{O}_{(g)}}\] is:

If heat of dissociation of \[CHC{{l}_{2}}COOH\] is 0.7 kcal/mol, then \[\Delta H\] for the reaction: \[CHC{{l}_{2}}COOH+KOH\to CHC{{l}_{2}}COOK+{{H}_{2}}O\]

One gram of an organic liquid X (molecular mass 78) liberates 160 J of heat on solidification. \[\Delta {{H}_{fusion}}\,\,(A)\] is:

Natural rubber is which type of polymer [DCE 2002]

The role of fluorspar \[(Ca{{F}_{2}})\] which is added in small quantities in the electrolytic reduction of alumina dissolved in fused cryolite \[(N{{a}_{3}}Al{{F}_{6}})\] is

Calculate the heat change in the reaction \[4\,N{{H}_{3}}(g)+3{{O}_{2}}(g)\to 2{{N}_{2}}(g)+6{{H}_{2}}O(\ell )\] at 298 K, given that the heats of formation at 298 K for \[N{{H}_{3}}(g)\] and \[{{H}_{2}}O(\ell )\] are - 46.0 and - 28.60 kJ \[mo{{l}^{-1}}\] respectively.